In an aircraft, there are a number of systems that include sections of metal tubing that are attached to the grooved inner circumferential surfaces of metal ferrules or connectors. These systems include hydraulic, fuel, and electrical systems, each of which requires conduits, portions of which are formed by metal tubing attached to ferrules. For each type of system, the standard method for attaching a tube to a ferrule is to carry out a swaging operation which forces the material of the tube against the inner surface of the ferrule and into the circumferential grooves to provide a secure attachment. For the type of attachment in which one end of the tube abuts against an internal radial shoulder inside the ferrule and the other end of the tube extends out of the ferrule, the attaching of the tube to the ferrule is conventionally carried out by a roller swaging operation. For the type of attachment in which both ends of the tube extend out of the ferrule, the conventional attaching procedure is an elastomeric swaging operation in which an elastomeric sleeve is confined longitudinally and compressed to expand radially to force the tube material into the grooves.
Each type of swaging operation has its limitations. Roller swaging operations result in a smooth inner circumferential surface formed by the tube material. Since there are no grooves on the surface, there is no means of measuring the degree of penetration of the tube material into the grooves on the ferrule without destroying the component formed by the tube and ferrule. In order to test the degree of penetration and thus the security of the attachment, it has been necessary to select a relatively small number of components and cut them into sections so that the degree of penetration can be observed. Roller swaging operations also take a relatively long time to carry out and sometimes cause undesirable elongation of the tubing material.
Elastomeric swaging is relatively quick and avoids the problems of material elongation and the need for destructive testing. However, known machines for elastomeric swaging and the known tooling for such machines are not designed to accommodate the type of attachment in which the tube abuts against a radial shoulder in the ferrule. A major problem that must be solved in order to adapt known machines to this type of attachment is the lack of any means for containing the elastomeric sleeve and preventing it from extruding along the drawbolt. Another problem encountered in using existing elastomeric swaging machines for swaging a number of additional types of ferrules is the high cost of the tooling required. In known machines, the entire split die must be changed for each different type of ferrule, and the die is a relatively large and expensive part of the machine.
The anvil is also a relatively large and expensive part of known elastomeric swaging machines. In the past, it has been necessary to replace the entire anvil when the portion of the anvil through which the drawbolt extends becomes worn. Generally, the other portions of the anvil have a considerably longer life than the portion through which the drawbolt extends. Thus, replacing the entire anvil because this one portion is worn is somewhat wasteful and unreasonably expensive. The present applicants conceived that, if the portion that wears first were made as a separate insert, such portion could be replaced separately without replacing the entire anvil and considerable expense could thereby be saved. The applicants have used an anvil with a replaceable anvil insert in elastomeric swaging machines since about 1980.
Apparatus for carrying out roller swaging or a similar operation is disclosed in U.S. Pat. No. 2,754,577, granted July 17, 1956, to C. A. Maxwell; No. 3,311,971, granted Apr. 4, 1967, to H. E. Hicks et al.; No. 3,683,658, granted Aug. 15, 1972, to R. C. Roeschlaub; No. 3,967,840, granted July 6, 1976, to R. A. McFall; and No. 4,411,456, granted Oct. 25, 1983, to C. F. Martin. The swaging of tube material into internal grooves or recesses is disclosed by Maxwell, McFall, and Martin. U.S. Pat. No. 3,595,047, granted July 27, 1971, to W. K. Fanning discloses an elastomeric forming operation in which O-ring grooves are formed in a tube by exerting axial pressure on an elastomeric member to cause it to expand radially and thereby force the tube material against a grooved die surface. One end of the elastomeric tube abuts the head of the drawbolt which exerts pressure on such member, and the other is received into a recess in an anvil which is referred to as a "collar".
Apparatus for forming material in which the material is held between a relatively rigid surface and a wheel having an elastomeric outer portion that at least partially surrounds the material is shown in U.S. Pat. No. 2,397,608, granted Apr. 2, 1946, to C. M. Johnson; No. 2,454,282, granted Nov. 23, 1948, to H. L. Johnson; No. 2,799,317, granted July 16, 1957, to H. A. Toulmin, Jr.; and No. 3,279,234, granted Oct. 18, 1966, to L. C. Ames. Apparatus for feeding material which has feed wheel portions that yield to accommodate varying thicknesses of the material is disclosed in U.S. Pat. No. 1,946,797, granted Feb. 13, 1934, to F. D. Kinney; No. 2,446,211, granted Aug. 3, 1948, to L. D. Clark; No. 2,803,126, granted Aug. 20, 1957, to J. A. Meyer; No. 2,804,968, granted Sept. 3, 1957, to H. A. Elliott et al.; No. 2,953,291, granted Sept. 20, 1960, to W. F. Huck; No. 3,438,231, granted Apr. 15, 1969, to E. W. Petzschke; No. 4,398,328, granted Aug. 16, 1983, to H. Takenaka et al.; and No. 4,460,433, granted July 17, 1984, to W. K. Boyd. U.S. Pat. No. 3,190,094, granted June 22, 1965, to F. J. Kutas discloses apparatus for splitting a metal drum which includes rubber tires that apparently urge the drum against a "parting" tool.
The above patents and the prior art that is discussed and/or cited therein and the other known apparatus discussed above should be carefully considered for the purpose of putting the present invention into proper perspective relative to the prior art.